iPhone 8 won't charge up from dead- stuck on bootup loop.

So I've plugged my phone in after it died and it won't come back to life- it gets to the apple logo screen, stays on it for a minute or two, then the screen goes back to black and then it restarts the process.

It doesn't seem to be responding to any attempt at a hard reset like I have seen suggested in other posts.

I have had issues with charging in the past- I was using a knock off cable not the one that came with the phone- but have since located a proper apple cable and am still having the same problem.

Any help asap would be appreciated as I need to use the phone for work in the next couple of hours.